Late Cenozoic sequence of volcanic eruptions in the Xilinhot area,Inner Mongolia
The sequence of volcanic eruptions is crucial for reconstructing the history of volcanic activity.The Xilinhot volcanic group stands out as having the greatest number of volcanoes and the longest duration of eruptions in the Cenozoic volcanic eruption zone of the Great Xing'an Range-to-Datong.This paper starts with the volcanic geology and identifies the superimposition relationship between volcanic deposits and sedimentary strata(e.g.,Lishi loess,Malan loess and black soil).The volcanic eruption sequence is comprehensively studied,and the relative timing and absolute age of eruptions are determined based on the volcanic structure,composition,morphological features,eruption types,volcanic rock types,and weathering degradation degree of volcanic cones,combined with optically stimulated luminescence(OSL)and 14 C dating methods.The Xilinhot volcanic group exhibits periodic changes in activity.The eruption sequence,in order from oldest to most recent,is as follows:Pliocene,Early Pleistocene,Middle Pleistocene(early and late stages),Late Pleistocene(early,middle,late,and end stages),and Holocene,totaling 9 eruption cycles.The Late Pleistocene was the period of highest volcanic activity.The most recent eruption age of the Gezishan volcano has been determined to be approximately 6800 years ago,confirming its status as a generalized active volcano.There are notable variations in eruption types and the degree of volcanic weathering and degradation among different cycles.Fissure eruptions occurred during the Pliocene,while fissure-central eruptions were predominant in the Early and Middle Pleistocene.Central eruptions occurred during the Late Pleistocene.The central-eruption volcanoes encompass various types,including Strombolian,Hawaiian,Maar,and Sub-Plinian eruptions.Notably,the discovery of Maar-type volcanoes in this area is a novel finding.The volcanic cones from the Middle Pleistocene and earlier have been almost completely eroded,while the volcanic landforms since the Late Pleistocene have been well preserved.Each eruptive cycle exhibits a characteristic evolution from alkali basalt to tholeiite,reflecting the periodic variations in the evolution of deep magma chambers and the intensity of tectonic activity in this area.
Late CenozoicEruption sequenceEruption typeGezishan active volcanoXilinhot
万方数据
维普
